The distance of various items to other items can create situations that may cause problems. For example, some types and categories of chemicals need to be kept apart, like acids and bases, or oxidizers and lubricants, among others. Further, some items should be kept in close proximity, such as a flammable chemical and the particular kind of fire extinguishers that may extinguish a fire with that chemical, like a metal and a metal fire extinguisher. Some household items need to be kept apart, such bleach and ammonia. In other examples, items may need to stay in proximity to each other, such as a traveler and her luggage. Currently, the enforcement of proximity rules is performed by signs, placards, warning labels on items, or manual attention to conditions and locations.
The same numbers are used throughout the disclosure and the figures to reference like components and features. Numbers in the 100 series refer to features originally found in FIG. 1; numbers in the 200 series refer to features originally found in FIG. 2; and so on.